FIG. 2.

Selection of rVVs using flow cytometry. (A) Phase-contrast microscopy and (B) fluorescent microscopy of 293T cells infected with rVVs expressing HIV-1 clade C envelope glycoproteins (EnvC) and GFP. Flow cytometry histograms of 293T cells infected with (C) wt VV (negative control) and (D) rVV–GFP–envC. The brightest cells were sorted and cloned by limiting dilution; viral particles were released by repeated cycles of freezing–thawing and used for infection of 143B Tk⁻ in the presence of BrdU.